The following block diagram (Fig.1-1) shows a communication system. For simplicity we assume that the signal is unchanged after the channel (no delay, no attenuation, no noise). Fig.1-1 The amplitude spectrum of the message signal, m(t), is shown in Fig.1-2 Fig. 1-2 (a)Sketch the amplitude spectrum of v1(t): |V1(f)|; label important frequencies and amplitude values. 10-10f (Hz)|M(f)|1× Channel×mixer mixer cos(2000пt)v2(t) vout(t)cos(2000пt)m(t) Modulator Demodulator
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